I have actually found power strips plugged into itself rather than the wall.  Doesn't quite work that way...

If the system won't power up, unplug the computer from the wall and wait for a few minutes before you plug it back in. Sometimes the power supplies will "lock up" and completely removing the power will reset them.   Unplug all devices from the computer except the keyboard, mouse, and video.   Sometimes external hard drives will keep systems from booting properly.

Try another USB port if the device fails on one, it may work on another.  A damaged USB port can also cause the computer to act oddly. Check inside the connector for broken or bent pins.  I have found improperly assembled computers with the grounding tabs shorting out USB ports.

Undoing the last change you made will sometimes get you back into the game...

Sorry,  no one ever reads the manual, and if your computer came with one it would be written in poorly translated Chinese.    Someone thought this should be on the checklist though...

If you spill water into your laptop don't try to keep using it.   Unplug it, remove the battery.  Call an expert.    Liquid on live electrical circuits will cause electrolysis, which will eat away at the copper circuits, and cause permanent damage.  If you remove the power completely and let it dry, there will be no damage.  Sticky liquids in keyboards are another story...

Don't format your hard drive or try to reinstall your operating system unless you have a backup of your data files, and the programs to reinstall, including all keys and install codes.   Even if your system won't boot or your hard drive seems to be trashed, the files and install codes can usually be recovered.   Please see our information on data recovery.

Don't open attachments unless you know what they are and you are expecting an attachment from that person.   Don't allow downloads and installs from strange websites.  Uncheck any optional installs, "free" toolbars, "free" security, system, virus scans from unknown companies.  Or unexpected things from what seems to be a known company or website.    Most problems I see today are fake antivirus or system scanning software just trying trick you into giving them your credit card.   Just reboot your system, if it's still there call for professional service.   Please see our section on "spyware".   And contrary to popular belief, Mac's are not immune to malware.

Part of finding the solution is to have a good description of the problem, or at least being able to duplicate or demonstrate the problem.